Because, in steadystate, windows disk protection is on, and any updates SEP installs is removed when the computer is restarted. So it seems unnessesary for liveupdate to be continuously checking and installing updates and using up pc resources.

It should be as simple as going to POLICIES -> LiveUpdate -> LiveUpdate Settings Policy Tab, and opening/creating a policy to edit. Then just clear all the checkboxes and assign it to the group of machines you want to disable updates on.

You could also (in a belt and braces fashion) click on the LiveUpdate Content Policies tab, create a new LiveUpdate Content Policy and disable updates for all content types (i.e. uncheck all the tickboxes). Assign this to the group as well and you're done.